Root-knot nematode (RKN) eggs have a multilayered structure that allows them to survive long-term in soil, serving as a major source of reinfestation. Dimethyl disulfide (DMDS), an efficient and environmentally friendly fumigant alternative to methyl bromide, shows significant inhibitory activity against RKN eggs, but its ovicidal mechanism remains unclear. This study evaluated the effects of DMDS on egg hatching under contact and fumigation treatments, utilizing scanning electron microscopy, confocal fluorescence imaging, transcriptomic, and proteomic analyses to elucidate the toxicological mechanisms. RT-qPCR and biochemical assays were used for validation. Results showed that under contact conditions, DMDS (75 mg·L⁻¹) reduced egg hatchability 88.7% within 48 hours, and the 24-h LC₅₀ was 53.2 mg·L-1. Under fumigation, 10–15 mg·L⁻¹ achieved 73.9% and 97.1% inhibition within 12 hours, and the 24-h LC₅₀ was 7.01 mg·L⁻¹. Morphological analysis revealed surface collapse, cracking, and chitin layer disruption, with leakage of internal contents. Transcriptomic and proteomic analysis indicated significant downregulation of chitin synthase and chitin-binding protein genes, consistent with decreased chitinase activity. Furthermore, detoxification pathways, including glutathione metabolism and cytochrome P450- mediated detoxification, were significantly activated, resulting in increased activities of antioxidant enzymes, including superoxide dismutase (SOD) and glutathione Stransferase (GST). In conclusion, DMDS effectively disrupts chitin synthesis, damages the egg shell barrier and membrane function, and induces oxidative stress and metabolic imbalance, thus blocking embryo development. These findings provide a theoretical basis for the application of DMDS as a green and efficient fumigant for controlling plant-parasitic nematodes.